It takes Doug 3 days to reroof a house. If Doug's son helps him, the job can be completed in 2 days. How long would it take Doug's son, working alone, to do the job?
the answer is 1 day because if it takes Doug 3 days by himself and if his son helps him and it takes 2 days with the both of them that means it would only take Doug's son 1 day.
